Combining magnetic field/temperature dual stimuli to significantly enhance gene transfection of nonviral vectors

Abstract

Monodisperse magnetic nanoparticles (MNPs) were prepared through an organic phase process, and the obtained MNPs were capped with poly[2-(2-methoxyethoxy)ethyl methacrylate]-b-poly[2-(dimethylamino)ethyl methacrylate] synthesized by surface-initiated atom transfer radical polymerization (ATRP). The MNPs-polymer brushes exhibited both superparamagnetic and thermoresponsive behaviors, and could condense plasmid DNA into nanocomplexes with a size of 100–120 nm at appropriate complexing ratios. Enhanced gene expression in COS-7 cells and HepG-2 cells was achieved under a magnetic field and variable temperature conditions due to magnetic force-facilitated internalization of nanocomplexes, and temporary cooling-triggered intracellular gene unpacking. Amazingly, combining magnetic field and temperature dual stimuli contributed to a 50–100- and 25–45-fold increase of the transfection efficiency in HepG-2 cells compared to conventional protocol and PEI25k, respectively.